Assessment of the root and canal morphology in the permanent dentition of Saudi Arabian population using cone beam computed and micro-computed tomography – a systematic review

Introduction Root canal treatment procedures require a thorough understanding of root and canal anatomy. The purpose of this systematic review was to examine the morphological differences of teeth root and their canals assessed using cone-beam computed and micro-computed tomography in Saudi Arabian population. Methodology An electronic search was conducted in PubMed / Medline, Scopus, Google Scholar, and Web of Science databases until January 2023 to retrieve related studies. “Root canal morphology,” “Saudi Arabia,” “Micro-CT,” and “cone-beam computed tomography” were used as keywords. A modified version of previously published risk of bias assessment tool was used to determine the quality assessment of included studies. Results The literature search revealed 47 studies that matched the criteria for inclusion, out of which 44 studies used cone beam computed tomography (CBCT) and three were micro-computed tomography (micro-CT) studies. According to the modified version of risk of bias assessment tool, the studies were categorized as low, moderate, and high risk of bias. A total of 47,612 samples were included which comprised of either maxillary teeth (5,412), or mandibular teeth (20,572), and mixed teeth (21,327). 265 samples were used in micro-CT studies while 47,347 teeth samples were used in CBCT studies. Among the CBCT studies, except for three, all the studies were retrospective studies. Frequently used imaging machine and software were 3D Accuitomo 170 and Morita’s i-Dixel 3D imaging software respectively. Minimum and maximum voxel sizes were 75 and 300 μm, Vertucci’s classification was mostly used to classify the root canal morphology of the teeth. The included micro-CT studies were in-vitro studies where SkyScan 1172 X-ray scanner was the imaging machine with pixel size ranging between 13.4 and 27.4 μm. Vertucci, Ahmed et al. and Pomeranz et al. classifications were applied to classify the root canal morphology. Conclusion This systematic review revealed wide variations in root and canal morphology of Saudi population using high resolution imaging techniques. Clinicians should be aware of the common and unusual root and canal anatomy before commencing root canal treatment. Future micro-CT studies are needed to provide additional qualitative and quantitative data presentations.


Introduction
The aim of an endodontic therapy is adequate cleaning and shaping of the root canals to eliminate microorganisms, filling of the canal three-dimensionally with an inert material to create a hermetic seal and placing a coronal restoration to avoid communication between peri-radicular tissues and the oral environment [1,2].However, the anatomy of the root canal is complex, that may vary from straight to curved canals or simple to more complex configurations in addition to wide range of variations in accessory canals and apical foramen anatomy [3,4].Such anatomical variations may vary among gender, sex and ethnicity [5].Untreated or missed canals has an impact on the outcome of an endodontic procedure [1,6].Therefore, adequate knowledge and meticulous understanding of the normal and unusual anatomy of human teeth are essential to avoid possible complications and failure of root canal therapy [7].
Over the decades, several invasive and non-invasive laboratory methods have been introduced to study the root and canal anatomy.An ideal method to study the root anatomy should be simple, accurate, non-destructive, and reproducible [8,9].Staining and clearing technique [10], scanning electron microscopy [11], 2D radiographic imaging [12] and 3D tomographic scanning including cone beam computed tomography (CBCT) [13] and micro-computed tomography (micro-CT ) [3] are the main laboratory methods to study root canal anatomy.In addition to this in-vivo methods include clinical studies consisting the clinical detection of root canals during the procedures [14] and observational CBCT clinically on various groups [15].
After reporting the pivotal role of radiography for determining the root canal length in 1899 by Kell, maxillofacial CBCT a 3D imaging technique was introduced in 1996 and was approved for dental use in 2001 by Food and Drug Administration (FDA) in the United States [16,17].It is a method obtained from computed tomography (CT) which provide data that is composed of identical dimensions at all sides permitting precise measurement of objects, hence, provide superior 3D images from received data with comparatively lesser radiation dose and time [18,19].The field of view is less but they are less invasive compared to conventional CT devices.Greater advantage of this technique is it construct the images in all three planes i.e., sagittal, axial and coronal, additionally images can be revolved in any plane avoiding superimposition and data can be reconstructed in their original spatial associations [17,20].
Similarly, micro-CT has gained popularity in endodontics due to its non-invasive, reproducible and nondestructive nature.It accurately gives the details of root canal morphology with higher resolution [21,22].Micro-CT demonstrates a wide range of qualitative and quantitative analysis of the internal and external tooth anatomy [23].
Various studies have been conducted on different populations to understand the root canal anatomy [7,[24][25][26][27].Similarly, several studies examined the root and canal anatomy of Saudi population revealed the morphological variations in permanent maxillary and mandibular incisors [28][29][30], maxillary first and second premolars [31], mandibular premolars [32,33], maxillary and mandibular first and second molars [34].Numerous studies are conducted on Saudi Arabian and sub-Saudi Arabian population.Hence, a systematic review would help to combine different studies and provide beneficial data that can guide clinically and in the research for better outcome.
This systemic review aimed to evaluate the root canal morphology of human permanent teeth in Saudi population using CBCT and micro-CT technology.

Research question
The search strategy was carried out using the condition, context, and population framework [35,36].The following question is considered: "What is the prevalence and variation of root canal configurations in the permanent dentition of the Saudi Arabian population, as assessed by CBCT and micro-CT studies?"Studies that only used CBCT and micro-CT were included.The context comprised of the studies conducted using CBCT and micro-CT on Saudi Arabia population.

Search strategy
A comprehensive electronic search was carried out in electronic databases, PubMed / Medline, Scopus, Cochrane, Embase and ScienceDirect without any restriction on the year of study until January 2023.Relevant articles were identified through manual searching of reference lists from included studies and relevant review articles.Additionally, we searched the tables of contents of key journals in endodontics and radiology to identify any potentially relevant articles that may not have been captured in the electronic searches.Gray literature includes unpublished or non-peer-reviewed sources such as conference proceedings, theses, dissertations, and reports.We conducted searches in databases such as OpenGrey, ProQuest Dissertations & Theses Global, and Google Scholar to identify any relevant gray literature related to our research question.Additionally, we searched relevant conference proceedings and contacted experts in the field to identify any additional gray literature sources.The number of articles retrieved from each database is presented in Table 1.Medical Subject Heading (MeSH) terms, keywords and other free terms combined with Boolean operators (OR, AND) were used for searching articles on PubMed, Scopus, Cochrane, Embase and ScienceDirect databases.Endnote X8 software imported the literature search results and removed duplicates.Abstracts were screened to check for eligibility criteria.Full articles of those that cleared were retrieved.

Data extraction
Two researchers (M.I.K and M.M) performed an electronic literature search and assessment for inclusion was done on 05 February 2023, using MeSH terms and keywords, as well as the Boolean operators "OR" and "AND" to compile relevant material using appropriate filters.Followed by data extraction and quality assessment.In case of disagreement, the third author (HMA) was consented and finalized.The keywords used were."Root canal anatomy", "Root canal morphology", "Root canal configuration", "Cone-beam computed tomography", "Micro-CT" and "Saudi Arabia".The required literature was then gathered using proper filters by combining these key terms with the Boolean operators "OR" and "AND" as shown in Table 1.

Eligibility criteria
Cross-sectional studies assessing root and canal morphology of permanent dentition using CBCT and micro-CT amongst Saudi Arabia population were included in this study.Editorials, case reports or expert opinion, commentaries, animal studies, studies done to evaluate any pathological altercations or findings in root canals and articles written in a language other than English were excluded Fig. 1.We did not seek additional information or clarification from authors of included studies.

Risk of bias assessment
Two reviewers (M.I.K and R.B) evaluated the studies based on the modified version of earlier risk of bias assessment tool [37].The included assessment is categorized as yes (adequate), unclear (not specified) and no (inadequate).The assessment was consisting of the following objectives: i. Sample size calculation (yes, no, and unclear): calculation of sample size is essential for any research as adequate sample size is important for generalizing the results and obtaining a valid conclusion.Sample size calculator and G* POWER can be used to calculate the sample size.ii.Reporting and quality of data: various factors affect the outcome of an image like voxel size, x-ray machine and software used.Hence when all the parameters are present it implies that the study is adequate.iii.Result description (yes, no, and unclear): main features in the results included the assessment of root canal configuration using different root canal classifications, detection of number of roots, canals, and accessory canals.Since most of the included studies in the present systematic review are CBCT studies, the outcome generally contained the abovementioned features.iv.Reliability of an observer (yes, no, and unclear): calibration of data is essential to minimize human error and to validate the results by reducing the potential bias.The trained observers are involved in this process.Intra-observer reliability is when a single observer conducts and repeats the same assessment whereas, inter-observer reliability is when two observers are involved in the same assessment at a specific time.Cohen's kappa test is considered as the valuable tool for this task.
Attrition bias (yes, no, and unclear): reporting of sample loss, proper sampling technique and sampling methods used in the study so that to cover the mentioned population.It highlights whether the population is regional or central.Attrition bias is not about the tooth loss, but it features about the population that belongs to specific region rather than generalizing the population.A total of 47 articles were eligible to be the part of this analysis.Data were independently extracted by two authors (M.I.K and R.B) and are summarized in Fig. 2.
Further to justify the studies they were classified as follows: Fig. 2 Risk of bias analysis of the 47 studies included in this review

Fig. 1 Criteria for Inclusion and exclusion of studies
A. Low risk of bias (i.e., studies meeting at least four of the assessment criteria): Fig. 3 represents the studies that met at least four of the quality criteria.B. Moderate risk of bias (i.e., studies meeting the criteria between two and four): Fig. 4 displays the studies that met the assessment criteria between two and four.C. High risk of bias (i.e., studies meeting less than two assessment criteria): Fig. 5 shows the data of studies that met less than two quality criteria and are classified as high risk of bias.

Outcome of study selection
Cross-sectional studies evaluating root and canal morphology of permanent dentition in Saudi Arabia population using CBCT and micro-CT were included in this study.Editorials, case reports or expert opinion, commentaries, animal studies, studies done to evaluate any pathological altercations or findings in root canals and articles written in a language other than English were excluded.Studies that used the different diagnostic tools other than CBCT and micro-CT were excluded.Further four rounds of screening were performed, where the first selection process deleted the duplicate articles, next unrelated articles were screened out through titles.In third round the abstracts were read to screened out the unrelated articles and finally the unrelated articles were screened out after reading the full text.Figure 6 shows the selection criteria as it follows the PRISMA guidelines.

Study charateristics
All the included 47 studies were carried out in the different regions of Saudi Arabia lasted for different time periods between 2013 and 2022 and were issued in various journals as listed in Fig. 7.

Number of teeth
Total number of samples involved and studied was 47,612, out of which 265 samples were used in micro-CT studies and 47,347 teeth were used in CBCT studies.Among the included micro-CT studies, maxillary second premolars were 100, 100 were maxillary first molars and 65 were maxillary first and second molars.The studies incorporated either maxillary teeth (n = 5,412) or mandibular teeth (n = 20,572) and studies including both upper and lower teeth were (n = 21,327).Among the total maxillary teeth, 657 were maxillary first molars, 351 were maxillary second molars.In case of mandibular teeth 8,603 were mandibular incisors, 316 were mandibular first premolar, 2400 were mandibular second premolar and 915 were mandibular first molars.Excluding the above results, few studies had mixed samples such as maxillary first and second premolars were 2362, maxillary first and second molars were 1,580, mandibular first and second premolars were 4014, mandibular first and second molars were 3,389 and 1433 were mandibular premolars and molars.

In-vivo studies
A total of fourty one in-vivo studies (CBCT studies) were included in the current systamatic review.

In-vitro studies
Six studies were in vitro where three studies used CBCT and three studies were performed using micro-CT.Storage media in CBCT studies was 2.5% sodium hypochlorite, 10% formalin and normal saline.While, 10% formalin and normal saline were used in micro-CT studies.ware were employed for interpretation of data.Morita's i-Dixel 3D imaging software was applied in eleven stdies,, Planmeca Romexis viewer software in nine studies, On Demand 3D software in five studies, CS 3D imaging software in four studies, Blue Sky Plan in two studies, Sidexis XG software was included in two studies and vision software in one study.The minimum and maximum voxel size was 75 to 300 μm.In order to classify the root and canal morphology of involved teeth in the studies, Vertucci's classification [38] was frequently applied (31) followed by the new coding system introduced by Ahmed et al. [39] in six studies, Pomeranz et al. classification [40] in two studies, Fan et al. [41] in one study, Calesen and Alexandersen [42] and Song et al. classification [43] in one study.

Specifications
The present systematic review included the studies conducted in the different regions of Saudi Arabia.It is evident from the literature that differences in ethnicity contributes to the variations in root canal anatomy [44].The results of the present study indicate that most of the anatomical features of the teeth were similar in Saudi Arabian population except for few studies where Saudi Arabian-sub regions had variations.Clinically, the population associated variations would help the clinician in understanding the anatomy properly and planning the treatment accordingly by avoiding any possible damage during the procedure.Sample size calculation is essential for any research as smaller size of samples can mislead the findings and causes greater variations in results.Numerous factors affect the sample size calculation such as study type, population, cost, research questions and objective [45].In the following systematic review, as many as 93.61 of the studies did not mention the method of sample size calculation which could be a weak point and can possibly alter the results.
Calibration is another important factor for attaining definitive outcomes.Calibrating is crucial to reduce the errors and minimize the potential bias, hence the investigators must be experienced and desirably calibrated to judge the clinical results and observations [46].Cohen's Kappa test is preferably used for calibration.In the present review, 36.17% of the studies did not mention calibration, since root canal anatomy is an important topic, the researcher must be calibrated to evaluate the methodology (Table 5).

Discussion
The present systematic review assessed the frequency of roots and root canal configuration in the permanent human teeth in the different regions of Saudi Arabian population.Both clinical and in-vitro data from various CBCT and micro-CT studies which provides information of morphological variations of teeth anatomy amongst Saudi population were included in the present review.The findings of this systematic review revealed significant variations in root canal morphology among different regions of the Saudi Arabian population.These variations can be attributed to a combination of factors, including genetic diversity, environmental influences, and regional differences in dietary habits and oral hygiene practices [5].Additionally, variations may arise from differences in sample size, examination techniques, and the experience of examiners [49,52].
It is important to note that root canal anatomy is inherently complex, and these variations emphasize the need for clinicians to approach endodontic procedures with a comprehensive understanding of the potential anatomical variations that may be encountered [92].Failure to do so can result in missed canals, inadequate cleaning and shaping, and ultimately, treatment failure [93].The risk of bias assessment, based on modified version of earlier risk of bias assessment tool was conducted for the included studies [37].This assessment is essential to evaluate the methodological quality of the studies and consider Sample size calculation is important in any research to generalize the results and obtain a justifiable conclusion.Sample size calculator and G* POWER software are usually used for that purpose.Sample size calculations was mentioned only in three included studies in this systematic review.In the case of observational studies, especially those involving anatomical evaluations, sample size calculations may not be applicable in the same way as in clinical trials or experimental studies [46].Sample size calculations are a crucial component of research design, primarily in experimental studies, to ensure adequate statistical power and the ability to detect meaningful effects.However, not conducting the sample size calculation or not reporting it weakens the study [94].
Similarly, calibration and quality of image are important for accurate results.Calibration confirms accurate measurements, while image quality affects the visibility of anatomical details.These factors are primarily important in studies where root canal anatomy is explored.Calibration establishes accuracy.Good quality of images is necessary for precise root canal analysis.Poor quality images provide unclear details and lead to inaccurate conclusions.Valid calibration and high-quality images enhance reliability [46].
Acknowledging the importance of radiography in endodontics for diagnosing and guiding the entire procedure, CBCT is regarded as the standard of care [95][96][97].The scanner of CBCT is simple, cost effective and less complicated, constructing 3D images which appreciates the tooth anatomy and their surrounding structures along with varied anatomy and teeth anomalies [98][99][100].It requires lesser radiation exposure and minimum period of time to produce the images [101].However, CBCT has limitations in terms of voxel size and resolution, which may affect the ability to detect fine anatomical details [93] and because the teeth are encased in bone with surrounding structures that may cause artifacts [102].
Micro-CT is another 3D imaging technique with higher resolution used to provide qualitative and quantitative analysis of the root and canal anatomy [103].It is non-destructive, non-invasive and reproducible method which gives detailed information of fine anatomical variations including the root apex morphology [104,105].As it is non-destructive method of imaging, it allows scanning of the same samples thus allowing examination of the volumetric features of the root canals after intervention (such as comparing shaping properties of certain endodontic file systems) and distinctively, the same data can be further used for mechanical testing [23].It is also applied in tissue engineering and biomechanics.It determines the stability of implants and mineral consideration of teeth [106,107].Micro-CT is typically used in research settings due to its higher cost and the need for specialized equipment [22].In studies that utilized micro-CT, researchers were able to examine root canal morphology at a finer scale, often revealing accessory canals, intercanal communications, intricate canal configurations and apical foramen anatomy [89].
The micro-CT studies included in this review provided detailed information on the root canal morphology [89][90][91].A study conducted in Easter province of Saudi Arabia, evaluated the root morphology and canal system of maxillary second premolars [89].According to this micro-CT study, single root (67%) and two canals (65%) was predominant finding along with complex root canal configuration where, type IV and V were found in majority of teeth (23%) followed by other type of configuration.In addition to the above findings, micro-CT provided other detailed descriptions of the apical foramen, apical delta, accessory canals, intercanal communications and isthmuses of maxillary second premolars as shown in Table 4.
Another micro-CT study included in this systematic review was conducted on maxillary first molars to detect extra root canal orifices which is usually difficult due to dentin ledge that can cover the floor of pulp chamber [90].Commonly it is approved that maxillary first molars have three or four pulp canals, but using 3D images by micro-CT this study evaluated the presence of three (7.01%),four (47.37%), five (35.09%) and six (10.53%) pulp canal orifices [90].
Similarly, one more micro-CT study was carried on maxillary molars [91].They are considered to have the most intricate root canal morphology than all maxillary teeth, because of the presence of second mesiobuccal canal in the mesiobuccal root which highly varies in its location.Higher failure rate of treatment is associated with failure to locate MB2 canals [108,109].As micro-CT produces images of higher resolution, this study evaluated the presence of MB and MB2 canals in maxillary molars (Table 4).Such micro-CT studies offer a complementary perspective to CBCT and underscore the importance of utilizing advanced imaging techniques for comprehensive anatomical assessments.
The anatomy of the root is complex which differs between the teeth as well in the same tooth among different individuals.Root length is not uniform, it may divide and rejoin at varying points and may possess extra canals or irregularities [110].Therefore, through knowledge of normal and possible variation of the root is essential to successfully perform the debridement, biomechanical preparation and obturation of canals, as lack of understanding and untreated roots adversely affects the outcome and prognosis of the treatment [111].
Results of this systematic review showed that maxillary central and lateral incisors had 100% single root and canal with Vertucci's type I configuration in the studies conducted among the population of Jazan city [84,85].While another study conducted in the Sakakah region, noticed variations in the canal configuration, where majority of maxillary central and lateral incisors had Vertucci's type I and 1 TN 1, however 12 out of 570 samples had type III and 1 TN 1-2−1 [30].This result could be due to differences in the region.
Canines are the longest teeth in the mouth and they are aesthetically important because of their position in the mouth and functionally essential due to their part in the development of occlusion [77].It was found that maxillary canine had 100% single root while some variations were detected in the canals and their configuration like single canal was in the range of 98-99% among the studies conducted in the Jazan city and Al-Kharj along with Vertucci's type I being the predominant (97-100%) followed by type III (1-2%) [76,77,84,85].However, one study conducted in the Riyadh presented different results where, type I was 97.94% followed by type V (1.1%) and type II and III were 0.47% respectively [78].This inconsistency in the outcome could be attributed to various factors such as regional differences, sample size and specifications of the evaluation tools [77].Saudi Arabia is a diverse country with a significant expatriate population, and this diversity can have implications for the observed variations in root canal anatomy.The included studies primarily focused on the Saudi Arabian population, but it is important to acknowledge that this population is not homogenous.Different regions within Saudi Arabia may have distinct ethnic compositions due to historical migration patterns [30].
The majority of mandibular incisors have single root and canal, but certain percentage of variations may be present such as second root canal, lateral root canal and apical delta [48].Among the included studies of different regions in the present systematic review, 100% of central and lateral incisors were single rooted [47,49,50,53,54].However, a very minor percentage of two roots variant was found in lateral incisors in Jazan city (0.5%,1%) [48,84] and 0.1% in Riyadh [52].Frequency of one canal and type I was higher in both the incisors.Evidence of two canals in the central incisor was 26.3-55.6% in the regions including Jazan, Qassim region and Riyadh [48-50, 52-54, 84, 85].While lateral incisors had two canals in the range of 30.8-55.6% [48-50, 52, 54, 84, 85].Higher frequency of two canals was noticed in the Qassim region and Riyadh (55.6% & 43%) [49,52].A worldwide prevalence study conducted by Martin et al., investigated the occasion of a second lingual canal in mandibular incisors in different countries, including Saudi Arabia, found the second canals in 34.7% and 33% of mandibular central and lateral incisors, respectively.According to this study, the presence of lingual canals in mandibular incisors is more in Asian, European and middle East countries than African and American countries.These variations can be attributed to different ethnicity, races, genetic differences or adaptation to specific environment, jaw size and migratory process [112].Type I configuration was higher (47.3-80.2%)followed by type III (13.6-45.7%) in the central incisors [47,48,50,[52][53][54].A study conducted by Mohamed, A.N., et al., the Qassim region displayed higher type III configuration (22.9%) than type I (20.5%) [49].Similarly, higher root canal configuration in the lateral incisors was type I (23.9-69.2%)followed by type III (22.1%42.5%)[47-50, 52, 54, 84, 85].Alterations in the results as mentioned above could be due to differences in the sample size, regions, and experience of the examiners [49,52].
Maxillary premolars are one challenging tooth type to treat endodontically due to variations in the root, canal and their configurations [55,56].Maxillary first premolars among the included studies performed in the different regions including Riyadh, Hail city, Jazan, Sakakah and Southern region of Saudi Arabia, predominantly had higher percentages of two roots (51.2-75.1%)compared to single root (23.7-40.7%).Three roots were also found in small percentage (0.5-3%) but they were present in males and absent in females [55-57, 81, 84-86].
Generally, mandibular premolars are single rooted, and their morphological variations are less.Mandibular first premolars had single root (80-99.5%),single canal (62.9-94.7%)and Vertucci's type I configuration (62.9-95.1%)along with certain variations [32, 58, 60-62, 81, 84, 87].Similarly, majority of second premolars were also found to be single rooted (80-100%), with one canal (71-98.6%)and type I canal configuration (91-97.9%)[32, 58-61, 81, 84].There was no evidence of C-shaped root canals in mandibular first and second premolar, however C-shaped configuration was found in both the premolars in one study of Jazan city, this could be due regional differences in the selected sample size [83].Ethnic diversity can contribute to variations in root canal morphology.Studies have shown that certain ethnic groups may have a higher prevalence of specific anatomical variations.This can be explained by a study of Martin et al.where prevalence of lingual canals in mandibular premolars was examined among population of different countries, there was presence of two canals (17%) and more than two canals (1%) in mandibular first premolar of Saudi population.Similarly two canals (3.3%) and more than two canals (1.3%) were also found in mandibular second premolar [114].Therefore, it is essential to consider the ethnic background of the population being studied when interpreting results and making clinical decisions [115].
Likewise, maxillary second molars were single rooted (0.3%), double rooted (2.7-6.6%),three rooted (92-99.3%)and four rooted (0.75-1.1%) and they also revealed the presence of MB root [64,[67][68][69].The prevalence of MB2 canals in maxillary first molars exhibited significant variation in the available literature.Prior research mostly concentrated on the morphology of roots and intricate canal shapes, as well as the influential elements of respondents' sex, age, and ethnicity.However, limited research has been conducted on the correlation between the existence of an MB2 canal and the arrangement of their apical portals of exit [116].
More often mandibular molars have two roots (89.6-97.1%),three canals (64.5-78.9%)but there can be evidence of three (9.8%) or four roots (2.9%) along with two or four canals and type I configuration being predominant in distal root whereas type IV in mesial roots.They also exhibit fusion of roots and discrete canal configuration.Further C-shaped canals and inter canal communication was also noticed [70,71,73,74,82].In addition to this, radix molaris (4.5%) in which, radix entomolaris was (4.2%) and radix paramolaris was (0.3%) in mandibular first molars were found in the Riyadh and Al-Kharj region [75].One study revealed the lower prevalence of radix entomolaris, and a second canal in the distal root of mandibular first molars among Saudi Arbian population compared to other populations in the East Asia geographic region and Asian ethnic groups, which had higher prevalence of radix entomolaris and extra canal in the distal root of mandibular first molars [117].
Strength This systematic review involved all CBCT and microCT studies that examined the root and canal anatomy in Saudi Arabian population.

Limitations
This systematic review included all studies without restrictions related to the voxel size of the CBCT images, which could affect the comparisons among different studies [118].system can also be used in future studies.A recent systematic review showed that the literature supports the advantages of the Ahmed et al. system, compared to other systems [119].• The use of PROUD reporting guidelines [46] for root and canal anatomy studies can also be helpful to standardize the reporting of study parameters and specifications.

Conclusion
In conclusion, this systematic review highlights the significant variations in root canal morphology within the Saudi Arabian population.These variations can be attributed to genetic, environmental, and regional factors, as well as differences in imaging techniques and demographic characteristics.CBCT and micro-CT was used in the present review to give knowledge about the root canal morphology of permanent dentition among different regions of Saudi population.It can be concluded from the study that widespread variations exist concerning the root canal anatomy, hence careful examination by suitable method is necessary.Mandibular incisors, mandibular premolars followed by maxillary molars were more commonly examined teeth among the included studies.Both the methods used were efficient in providing data of normal and altered root and canal anatomy of teeth with significant information.

Fig. 4 Fig. 3
Fig. 4 Moderate risk of bias: studies that met between two and four of the criteria (Green-Yes; Red-No; Yellow-Unclear)

Fig. 5
Fig. 5 High risk of bias: studies that met less than two criteria (Green-Yes; Red-No; Yellow-Unclear)

Fig. 7
Fig. 7 Included articles published in the respective journals Where, JCDP: The Journal of Contemporary Dental Practice; PJMHS: Pakistan Journal of Medical & Health Science; CCID: Clinical, Cosmetic and Investigation Dentistry; ERMPS: European Review for Medical and Pharmacological Sciences; JPBAS: Journal of Pharmacy and Bio allied Sciences; PBEOCI: Pesquisa Brasileira Em Odontopediatria Clinica Integrada and IJOSDM: International journal of oral science and dental medicine

•
Future research in this field should aim to address demographic factors and their potential impact on root canal anatomy in Saudi Arabian population.• In future research, the integration of micro-CT and CBCT data could provide a more comprehensive understanding of root canal anatomy.Comparative studies that evaluate the accuracy and diagnostic capabilities of these imaging modalities in clinical practice would be valuable.• Future research in the field of endodontics should consider the influence of ethnicity, age, and gender on root canal anatomy in different Saudi Arabian sub-populations.Furthermore, the integration of advanced imaging modalities.• Clinicians should be aware of the potential anatomical variations they may encounter and consider the use of advanced imaging techniques when necessary to improve the quality of endodontic treatment.• Sample size calculation has to be considered in future studies related to root and canal anatomy in Saudi Arabian population.• The application of Ahmed et al. classification

Table 1
Search strategies using keywords phy OR Micro-CT) AND (Saudi Arabia) 08 EMBASE "Root canal anatomy" OR "Root canal morphology" OR "Root canal configuration" AND "Cone-beam computed tomography" OR "Micro-CT" AND "Saudi Arabia" 08 Total 466

Study Reference Sam- ple Size Sample type CBCT machine Voxel size (Resolution) Software used Classification System Technique Results Conclusion
8% of mandibular canines had one root and double root was seen in 0.2% which were men.98% of females had one canal while 92.4% of single canal was seen in male.Predominant canal configuration was type I (95.4%) followed by type II (2.6%), type III (1.8%) and type IV (0.2%).

Table 2
Characteristics of the included CBCT in-vivo studies 100% one root and 99.9% of lateral incisor had one with 0.1% two roots.One canal was noted in 58.8% and two canals in 41.2% with no difference between central and lateral incisor but women had increased frequency of two canals (57.09%) than men (42.9%).100% in lower central and lateral incisor while 98.4% of one root was seen in canine.Type I configuration was major among the lower anterior whereas 36.5% of type III was noted in central and 31% in lateral incisor.Regarding the sex, females had higher frequency of type I than type III while males had higher chances of type III.

Table 3
Characteristics of the included CBCT in-vitro studies

Table 4
Characteristics of the included Micro-CT studies

Table 5
Specifications of the studies